Phenolic ester resins



Patented Aug. 18,1953

UNITED sures roFricE 2,649,422 VFPHENOLIO-ESTER RESINS David Aelony,Minneapolis, Minn, assignor to General Mills; Inc:, a corporation ofDelaware NoDrawing. -Application February-6,1950,

Serial No. 142,709

- Ill-"(Dlaim'sL 1 i The esters of the present invention .are derivedfrom phenol formaldehyderesins "or a'par ticular type as willbeidescribed more fully hereinafter. These resins are esterified withhigher unsaturated fatty acidsiderived" from drying oils or semi-dryingoils suchas linseed and soybean oil acids. The phenol formaldehyderesins themselves may be water-white and. crystal-clear,.and theesterproduced from these resins may" be colorless depending upon thecolor of the fatty acids used foriesterification. The esters dry'tohard, tough, resilientfilmsfithe'rateof drying being dependent upon thedegree of 'unsaturation of; the fatty acid employed; and the averagemolecular weight of: the "resin. g It is therefore an object of-thepresentinvention' to provide novel" esters of phenol formaldehyde'resinsof a particularitype.

It is another object of the present invention to provide higherunsaturatedf fattyacid esters of phenol formaldehyde resins ofaparticular type, the esters being in the naturei'ofidrying oils andbeing capable of drying toiha'rd, tough; resilient films.

The phenol formaldehyde resins used for esterification in the presentinvention are those which contain an average of from about 4 to aboutphenol groups in the'resinmolecule andwhich are derived by the acidcatalyzd'condensationof from 2 to 2 moles of formaldehyde per 4=-mo1esof phenol. The resins'a're preferably substantially free frommethylol'groups, or at most contain only a'few such groups. If there isa substantial number of methylol groups-present in the resin, there isachance for further increase in the molecular weight of theresinthrougheom densation with itself :during subsequent esterification.In some instances any substantial com densation occurring duringesterification may cause the esterification mixture to gel. F Resinswhich are substantially free f-romwmethyl'ol groups may be made byslowly adding formaldehyde to an excess of phenol containing an acidcatalyst andqthen carrying out the usual acid catalyzed condensation.'After the condensation is "com- 'pleted, theresi'n may be cooledunder'nitro'gemin which event, it may, be .made. water-whiteaandcrystal-clear.

' Resins having an averageuof from :aboutlev to about 10 hydroxyl 1groups: per :molecule: may be made by employing fromc2cto about .2 /2:moles of formaldehyde per 4 moles of phenol. Theprocess is simpleand-inexpensive to'conduct. -Any excess v.=I, h enol may be recovered.readily {as may :be the bis and-trig compounds-allof:which mayberecovered by simply distilling them from-the resin reaction mixture. Theresins .prepared as herei-n described are insoluble inffattyoils. Theresins maybe prepared from-phendlitself and may be either of theortho,orthotype or of generally lessdesirable.

Theresins describedabove may be esterified with'fatty acids of thedrying or' semi-drying type. These acids may "be the mixed acids of adrying or semi-drying oil, such as the mixed-acids of soybean oil,linseed oil; tung'oil, perilla'o'il,

oiticicaoil, and the like. Theymay likewisebe selected fractions of suchoils ora'ctually isolated fatty'acids of such oils whioh have a dryingor semi-drying characteristic. Even the'oleic acid esters dry tack-freein an extended period of time,

but generally it is desired to-use acids having an iodine number of atleast 100 and preferably at least 110.

.The esterificationmay be carried out by simply heatingth'e resinsthefatty'acids in the absence ofacatalyst at temperatures in eX'cessof200 0., preferably from"230-'250 0., or in the presence ofzanesterlification catalyst at temperaturesof. from 150- 250": C.The-waterliberated during the reaction-maybe-taken off, condensed,

and the reaction carriedon untilthe product has a desired acid number.It has-been found that it is usually desirable tocarry on theesterification to the point at which a minimum of about ofthe hydroxylgroupshave been esterified.

Below this point excess free phenolic hydroxyl groups result inpoorercolor for the resultant product, and also result in" poorer alkalistability. W here the degree ofesterification is from 60-70the-productshave a reasonable degree of color and alkali stability andare useful in'protective'coatings. It is preferred,'' however, to carryon the esterification to the point at-which' from -100% of-the hydroxylgroups are esterified. The productsof-bestcolor stability and alkalistabilityare obtained within this range.

The time required foresterification varies widely with the type of resinemployed, the extent of esterification desired, and-whether or not acatalyst is used. In the absence of a catalyst. time periods of from"18-24 hoursare required for degrees of esterification of 60% or higher.A time period of from '812" hours may be required. to

zinc l stea-rate' as amatalyst. "The same esterification may be obtainedin 6 hours with boric ification process, depending upon the variousconditions which exist.

The following examples will serve to illustrate the invention:

Example 1 Seven hundred fifty-two grams of phenol .(8 moles) and 2 g. ofconcentrated HCl wereagie tated and heated to 80 C. 364 cc. of formalin(4 moles) were then added over a period of three hours. Agitationandreflux were continued for five hours; andthe product was then firstevaporated-under a water pump. Thereafter, the residue was distilled at50 until the pot temperature reached 310 C. The distillate weighed 128g; (bis and tris compounds), while th residue weighed 518 g. and had ahydroxyl number of 628, a molecular weight of 512, and a melting pointof 98-105 C.

One hundred grams of this phenolformaldehyde resin, 310 g. of soybeanoil fatty acids, 4 g. of zinc stearate, and 50 cc. xylene were refluxedand agitated under a Stark and Dean tube for 46 hours at 235-240 C. 90%of the theoretical quantity of water distilled over. The product wasfirst evaporated and then distilled up to 270 C. (pot temperature) at30a. The distillate Weighed 21 g. and the residue weighed 374 g., had an1.5195, an acid number of 6.3, a hydroxyl number of 15.0, asaponification equivalent of 371.5, and a viscosity of 3XZ6. Two g. ofthe product were dissolved in 1 g. of xylene and 0.2 cc. of drier. Itgave a hard colorless film in ten minutes'at 130 C. At room temperatureit dried in 30 minutes.

Example 2 One hundred grams of the phenolformaldehyde resin of Example1, 248 g. of soybean oil fatty acids, 4 g; of zinc stearate, and 50 cc.of xylene were refluxed and agitated under a Stark and Dean tube for 28hours at 225-240 C. The prodnot was treated as above described, butthere was no distillate. The residue weighed 336 g. and had an 1%1.5255, an acid number of 5.0, hydroxyl number 53, saponificationequivalent 344, and a viscosity 1.14 Za.

Example 3 Seven hundred fifty-two grams of phenol (8 moles), 2 g. ofconcentrated HCl were agitated and heated to 80 G. Then 384 cc. offormalin (4% moles) was added over a period of 3 hours. The product wasworked up as described in Example 1 to yield a distillate weighing 120g., and a residue weighing 539 g. and having a hydroxyl number of 624, amolecular weight of 526, and a melting point of 100-109.5 C.

One hundred grams of the above described phenolformaldehyde resin, 308g. of soybean oil fatty acids, 4 g. of zinc stearate, and 50 cc. xylenewere refluxed and agitated under a Stark and Dean tubefor 24 hours at227-245 C. The prodnot was worked up as described in Example 1 to yielda distillate weighing 28 g. and a residue weighin 365 g. and having an11. 1.5179, an acid number of 3.8, hydroxyl number of 8.1,

saponification equivalent of 341.7, and a viscosity I of Z4Z5. Theproduct when mixed with drier dried to a hard but slightly wrinkledfinish 4 A ten minutes at 130 C. At room temperature it dried in 50minutes to a smooth finish.

, Ew mple4 One hundred grams of thephenol formaldehyde resin of Example3, 4 g. of zinc stearate,

248 g. of soybean oil fatty acid, and 50 cc. of

xylene were agitated and refluxed under a Stark and Dean tube for 22hours at 230-240 C. ihe

product was treated as above described. There was no distillate, and theresidue weighed 335 g., had an 15, 1.5210, an acid number of 4.8, hy-

, droxyl number of 12.8, saponification equivalent of 345.5, and aviscosity of 2.8 Zs. Three g. of the product were mixed with 0.3 cc. ofdrier. A partly frosted hard film formed in ten minutes at 130 C. Atroomtemperature a good film formed'in two hours.- 7 Y j Seven hundredfifty-two grams of phenol and 2 g. of concentrated HCl were heated to vC. Then 405 cc. of formalin (5 moles) was added over a period of threeand one-half hours. The product was then treated as described in Example1, and a distillate weighing 102 g. was obtained. The residue weighed572g. and had a molecular weight of 675, a melting point of 101-111 C.,and a hydroxyl number of 625.6.

One hundred grams of. this resin, 4 g. of zinc stearate, 290 g. ofsoybean oil fatty acid, and 50 cc. xylene were refluxed and agitated for47 hours at 230-250 C. The product wasworked up as described above toyield a distillate weighing 13 g. and a residue weighing 353 .g. andhaving an n 1.5197, a hydroxyl number of 24, an acid number of 2.3, anda saponification equivalent of 458. Two g. of the product were dissolvedin 2 g. xylene and 0.2 cc. of drier. It dried in ten minutes at C. andin 35 minutes at room temperature.

1 Example 6 On hundred grams of the phenolformaldehyde resin of Example5, 4 g. of zinc stearate, of soybean oil fatty acids, and 50 cc. ofxylene were refluxed and agitated under a Stark and Dean tube for 46hours at 230-237 C. The product was worked up as described for the otherexamples. There was no distillate. The residue weighed 332 g. and had ann 1.5215, a hydroxyl number of 16.5, an acid number of 1.8, asaponification equivalent of 350.3, and a viscosity of Z5-Zs. Three g.of the material were mixed with 0.3 cc. of drier. At 130 C. a good filmwas formed in ten minutes, while at room temperature the film set in 1hours.

. Exampl 7,

One hundred grams of the phenolformaldehyde resin of Example 3, 3 g.zinc stearate, 290 g. of a fatty acid fraction of tall oil containingapproximately 50% of oleic acid, 40% of linoleic acid, and the remainderlinolenic acid and rosin acids, were refluxed and agitated togetherwith. 50 cc. of xylene under a Stark and Dean tube for 31 hours at235-270 C. The product was worked up as usualto yield a distillateweighing 9 g. and a residue weighing 365 g-;, and having an 77.

1.5175, a hydroxyl number of 3, an acid numberof 4.2, and asaponification equivalent of 347.8,

The solution Y .J Example 8 One hundred gramsof the phenolformalde-hyderesin of Example 5,4; g. of zincstearate,-230- g. of the: fatty acidfraction of :talloilas-described in the previous example; and:50 cc; ofxylenewere refluxed: and agitated-under :a-Stark and Dean tube: forhours at 22'7-235 C. The product was worked'up-asusual to yield adistillate weighing 9 g.- and a residue weighing 358 g.,-and having an.71. of 151-73,- a hydroxyl'number of -3--.3, an acid number 0f'415, asapon'ification equivalent. of 347.7, and-'a-viscosityof Z4..Three-gramsof the product were mixed-with 0.300; of drier. *A filmformed from this solution dried nicely in ten'minutes at 130 C. and inthree hours at room temperature.

Example 9 One hundred grams'cf the phenolformaldehyde resin-of Example1, 4 g. of zinc stearate, 310 g. of linseed oil fatty acid, and 50 cc.xylene, were agitated and refluxed under a Stark and Dean tube for 27hours at 225-235 C. 'The'prodnot was evaporated, and then stripped at255 C. at 10 The distillatewei'ghe'd g.; the residue weighed 335 g.-(small loss), and had "an n 1.5245, an acid number of 6, a hydroxylnumber of 37, a saponification equivalent of 375. Two g. of the productwere dissolved in 1 g. xylene and mixed with .2 cc. drier. A good filmwas formed in ten minutes at 130 C. At room temperature it set inminutes.

. Example 1 0 *729 cc; formalin (9 moles) were added to a solution of'"60 cc. acetic acid-in 1504 g. phenol over a'period of '65 minutes. "Themixture" was then refluxed and agitated for 10 hours. There after themixture was evaporated and stripped to a temperature of 305 C. at 120microns. The distillate was a liquid weighing 240 g.; the residueweighed-941 g. The Gardner viscosity of a 50% solution of the resinin'butanol'was J K. The resin had a molecular weight of 691-736,a'capillary melting point of 92-97" 0., anda hydroxyl numberof 523-524.

.100 gof-the above resin-4 g. zinc-stearate, 160 g. distilledmixedsoybean oil acids, and '45 cc. xylene wereagitated and refluxed under aStark and Dean tube'for' 8 hours at a temperature. of 235'-245- C. 10.4cc. of water wererecovered: indicating about 60% esterification.

Emwmple 11 1504'g. of 'phenol'and 41g. oxalic acid were heated andagitated while 729cc; formalin (9 molesrwere added over a period of 2hours minutes. Befiuxing was continued for 10 hours andthe'mixturewasthen allowed to stand overnight. The product was evaporated, th'enstripped to a temperature of 303 C. at 550 microns. The distillateweighed 247 g.; the residue -1035 g. The residue hadamelting pointof 93-00w C., molecular weight 767.

100 g; of the above resin, 160gdistilled mixed soybean oil fatty acids,4 g. zinc stearate, and cc. of Xylene were agitated and refluxed under aStark. and Dean tube for l -hours during which time 10.3 cc. ofwaterwere' distilled over, .indicatingapproximately :;-esterification.The product was evaporated to 255 g. The resultant product was made intoa 60% solution in mineral spirits, the solution treated withdiatomaceous earth and filtered. The filtered solution was mixed withdrier and films cast on tubes and plates. "me 'filmsdried tovnc transferin 80 minutesyand" Werettackfree -to foil'in 8 hours. Rockerhardnessafter-24 hours was 6,after 4 days 10,'acidnumber 8.6;viscosity 4.4 Zs.The film 'failed-in 5% NaOHrin 27 minutes. The product wasstablein'boiling water after 2 hours, and: was stable: in cold iwaterafter '7 2 hours.

In the preparation ofthe resin the number of phenolic-groups intheimolecule' maybe varied from" 4' to .10. Theiiexa'ct size'of thephenolic resin moleculev may be governed by-the type of acid" and thedegree of' e'sterification' whichv is to be em'ployed. "When'ia' highlyunsaturated acid is to be employed:for esterification, and whentheesterification is to be carried on to a very higlr'degree, thereis'the possibility of gelation occurring during the esterification whena phenolic' resin having lophenolic groups is employed. It' ispreferred, therefore, to employ less rapid drying acids for high"molecular weight resins, or"to have a'reduc'ednegree of est'erification.Similarly when ph'enolic'"'resins having only 4 phenolic groups-permolecule are employed, it is preferred toiemp'loy'more rapid dryingacids and to carry the degreexof' esterification' to a higher extent,such that' aproductwhich dries within a reasonableirperiodi-of timev andwhich results in a" film offreasonable"hardness is obtainab'le.

Variation is also possibledn the removalof the bisand tris compounds.These materials may be left in if desiredrbut ingeneral they doincreasethe drying time and'result in softer films. In some applications thismaynot be objectionable and accordingly. the bis and tris compounds may beleftin entirely. Inothers it may be desirable to remove the his I andtris com pounds to somei'extent' and in other applicationsitmaybe'desirable toremove the his and tris compounds? completely.Thebest products are obtained when" the bis and tris compounds areremovedtinasmdchas such products have very rapid drying rates andproduce exceedingly hard films.

It will be apparent 'from the'previousdescriptionandvthenumerous:examples that there is considerable'variation"possiblein the types of resins and esters "which may be prepared. Considerablevariation is alsolpossible in the specific typeof drying orJsemie'dryingoil acid employed and in the extent of esterification.

Onua' commercial scale 1: process may be carried' out verysimplyhandeasily in a single kettle. The 'phenol: formaldehydecondensation may be carriedcout'in the kettle, after-which the excessphenol'and also the bisrand tris compounds, if desired, mayberemoved:byldistillation. The fatty'acids and'the esterificationcatalyst,r'if one is employed, may then 'be added and the esterifiothervariationsarezpossible without departing from the spirit thereof.

I claim as my invention:

1. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average of from about 4, to about 10 7 V phenolic groupsper molecule and being derive from the acid;catalyzed condensation offrom 2 to 2 /2 moles of formaldehyde per: 4 moles of phenol and beingsubstantially free from phenol and bisphenols, the hydroxyl groups ofthe resin being esterified at least about 60% by means of an unsaturatedhigher fatty acid having at least semi-drying characteristics, saidester being substantially free from acetyl groups.

2. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average 'of from about 4 to about 10 phenolic groups permolecule and being derived from the acid catalyzed condensation of from2 to 2 /2' moles of formaldehyde per 4' moles of phenol and beingsubstantially free from phenol and bisphenols,'the hydroxyl'groups ofthe resin being'esterified at least about 60% by means of the mixedacids of soybean oil, said ester being substantially free from acetylgroups.

3'. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average of from about 4 to about 10 phenolic groups permolecule and being derived from the acid catalyzed condensation of from2 to 2 moles of formaldehyde per 4 moles of phenol and beingsubstantially free from phenol and bisphenols, the hydroxyl groups ofthe'resin being esterified at least about 60% by means of the mixedacids of linseed oil, said ester being substantially free from acetylgroups.

4. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an averageof from about 4 to about 10 phenolic groupspermolecule and being derived from the acid catalyzed condensation of from2 to 2 /2 moles of formaldehyde per 4 moles of phenol and beingsubstantially free from-phenol and bisphenols, the hydroxylgroups of theresin being esterified at least about 70% by means of an unsaturatedhigher fatty acid having at least phenol and being substantially freefrom phenol and bisphenols, the hydroxyl groups of the resin beingesterified at least about 70% by means of the mixed acids of soybeanoil, said ester being substantially free from acetyl groups.

'6. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontainingan average of from about 4 to about '10 phenolic groups permolecule and being derived from the acid catalyzed condensation of from2 to 2 /2 moles of formaldehydeper 4 moles of phenol and beingsubstantially free from phenol and bisphenols, the hydroxyl'groups ofthe resin being esterified'at least about 70% by means of the mixedacids of linseed oil, said ester being7 substantially free from acetylgroups.

'7. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average of from about 4 to about 10 phenolic groups permolecule and being derived from the acid catalyzed condensation of from2 to 2 /2 moles of formaldehyde per 4 moles of phenol and beingsubstantially free from phenol and bisphenols, the hydroxyl groups ofthe resin being substantially completely esterified by means of anunsaturated higher fatty acid having at least semi-dryingcharacteristics, said ester being substantially free from acetyl groups.

8. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average of from about 4 to about 10 phenolic groups permolecule and being derived from the acid catalyzed condensation of from2 to 2 /2 moles of formaldehyde per 4 moles of phenol and beingsubstantially free from phenol and bisphenols, the hydroxyl groups ofthe resin being substantially completely esterified by means of themixed acids of soybean oil, said ester being substantially free fromacetyl groups.

9. A liquid, low acid number ester of an oilinsoluble phenolformaldehyde resin substantially free from methylol groups, said resincontaining an average of from about 4 to about 10 phenolic groups permolecule and being derived from the acid catalyzed condensation from 2to 2 moles of formaldehyde per 4 moles of phenol and being substantiallyfree from phenol and bisphenols, the hydroxyl groups of the resin beingsubstantially completely esterified by means of the mixed acids oflinseed oil, said ester being substantially free from acetyl groups.

10. Process of producing unsaturated higher fatty acid esters of phenolformaldehyde resins having from 4 to 10- phenolic groups per molecule,which comprises slowly adding formaldehyde to phenol in the ratio offrom 2 to 2% moles of formaldehyde per 4 moles of, phenol, condensingthe phenol and formaldehyde in the presence of an acid catalyst,evaporating water from the reaction mixture to produce the phenolformaldehyde resin, distilling out phenol and phenol formaldehydecondensation products containing less than 3 phenolic groups permolecule, adding unsaturated fatty acids and an esterification catalystto the reaction mixture, heating the reaction mixture to anel'evated'temperature for an extended period of time, removing waterformed during the reaction, and continuing the reaction until at leastabout 60% of the hydroxyl groups of the phenol formaldehyde resin havebeen esterified with the unsaturated higher fatty acid.

DAVID AELONY.

References Cited in the file of this patent V UNITED STATES PATENTSNumber Name Date 1,924,052 Somerville Aug. 22, 1933 2,091,965 CherrySept. 7, 1937 2,134,388 Cherry Oct. 25, 1938 2,544,365 Sorenson Ma'r. 6,1951 FOREIGN PATENTS.

Number Country Date 570,367 Great Britain July 4, 1945 572,822 GreatBritain OctQ25, 1945

1. A LIQUID, LOW ACID NUMBER ESTER OF AN OILINSOLUBLE PHENOLFORMALDEHYDE RESIN SUBSTANTAILLY FREE FROM METHYLOL GROUPS, SAID RESINCONTAINING AN AVERAGE OF FROM ABOUT 4 TO ABOUT 10 PHENOLIC GROUPS PERMOLECULE AND BEING DERIVED FROM THE ACID CATALYZED CONDENSATION OF FROM2 TO 21/2 MOLES OF FORMALDEHYDE PER 4 MOLES OF PHENOL AND BEINGSUBSTANTIALLY FREE FROM PHENOL AND BISPHENOLS, THE HYDROXYL GROUPS OFTHE RESIN BEING ESTERIFIED AT LEAST ABOUT 60% BY MEANS OF AN UNSATURATEDHIGHER FATTY ACID HAVING AT LEAST SEMI-DRYING CHARACTERISTICS, SAIDESTER BEING SUBSTANTIALLY FREE FROM ACETYL GROUPS.